Legacy is one of the most important ideas in DC Comics and given this many heroic and villainous identities are used by more than one character. The identity of Doctor Light is unique in that as the Red Hood, it is one of the few monikers to be used by both a hero and a villain.

Arthur Light and Kimiyo Hoshi have both called themselves Doctor Light, making the name represent both an obscure but important crime-fighter and one of the Justice League's most vile and personal enemies.

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Arthur Light 

Doctor Light sulks on a chair under a ceiling light in Identity Crisis

Created by Gardner Fox and Mike Sekowsky, Arthur Light first appeared in Justice League of America #12 in 1962. He was initially portrayed as a criminal physicist who used his scientific knowledge to manipulate light and battle the Justice League. He was originally only capable of doing so through the use of a special suit but his body later developed the ability to do so independently. Secret Origins #37 by Craig Boldman, Ty Templeton, Mike Parobeck, Ken Branch, and Anthony Van Bruggen delivered a retcon in which Light had stolen the suit from his partner Jacob Finlay, who had created it and operated as a small-time superhero using the Doctor Light name.

Arthur Light served as an enemy to multiple DC Universe heroes for decades. Eventually, he started to be portrayed as more of a comedic nuisance than a serious threat and was always easily defeated by the likes of the Justice League and the Teen Titans. "Identity Crisis" revealed the dark reason behind this shift, as during the Justice League's satellite era Light broke into the Watchtower and sexually assaulted Sue Dibny. After the League stopped him Hawkman, the Atom, Zatanna, and the Flash voted to not only use Zatanna's powers to erase Light's memories of their secret identities but also to modify his personality so he wouldn't ever commit such a vile act again. The process was only partially successful, and gave Light his later bumbling persona. When the rest of the superhero community discovered what had happened, and that the secret sect of the League had also erased Batman's memory of the incident, it divided them. During the series, Light recovered his memories, which increased his hatred of the Justice League and other heroes.

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Kimiyo Hoshi 

Created by Marv Wolfman and George Pérez, Kimiyo Hoshi first appeared in Crisis on Infinite Earths #4 in 1985. An astronomer working in Japan, Kimiyo became obsessed with studying the Crisis despite the mounting danger it posed. She was shown as being selfish and rude to her peers. The Monitor used energy from the Vega star to give her light-based superpowers, turning her into Doctor Light, who he recruited. Although Kimiyo worked with the world's other superheroes to battle the Anti-Monitor she initially maintained her bad attitude. It was only after Supergirl sacrificed herself to save the world that Kimiyo resolved to improve herself as a person and become a more dedicated hero. In post-Crisis continuity, in which Supergirl no longer existed, she was said to be inspired by other heroes. Kimiyo has served on various superhero teams such as the Justice League (including the International version) and the Doom Patrol. In addition to her light-based abilities, Kimiyo also has the power of flight.

Kimiyo and Arthur have encountered and battled one another multiple times, including during "Blackest Night", when Arthur was resurrected as a Black Lantern. He nearly overwhelmed Kimiyo, but after he threatened her family she destroyed him. The New 52 radically altered both of them and their histories. Arthur was portrayed as much more heroic, serving on the Justice League of America (although reluctantly) and the two were once married and had three children together. A later appearance by Arthur hinted that he did, however, have a villainous past, which was possibly meant to retcon him to be more like previous versions.

Despite Kimiyo's long history of heroism, Arthur's villainy has defined the Doctor Light legacy. Although "Crisis on Infinite Earths" is a more famous story overall, Kimiyo's part in it is not one of its more famous elements, and Arthur's involvement in "Identity Crisis" has made it the defining Doctor Light story. The characters' multimedia appearances have also contributed to associating the Doctor Light name with villainy. Arthur has appeared in more animated and live-action properties and has been given more significant roles in them. Kimiyo's number of appearances and complexity of roles is more limited and the only live-action version so far, played by Emmie Nagata, in The Flash TV series was changed into a villain.

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